>>4710964 lb
Exactly, man sized hole in a half hour. Layered security
I think the 6" box is 3/'8" and cored with either a glass fiber or Kevlar fiber reinforced concrete sometimes used in security applications.
That is a fuckton of concrete. It would be better.
Somebody yesterday memed a moat which got me thinking a canal. Army could run it like they Ran the Panama and problem solved. Big $ tho